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Number of digits in Mersenne primes with a prime number of digits.
0

%I #5 Mar 31 2012 10:32:39

%S 2,3,19,157,2917

%N Number of digits in Mersenne primes with a prime number of digits.

%e a(4) is M21, the 21st Mersenne prime with prime digit count of 2917

%Y Cf. A028335.

%K nonn,base

%O 1,1

%A _Enoch Haga_, Dec 18 2001